In #813 the capability was added to rename and delete attributes. We should enhance this capability to insert attributes as well. This will eventually be used in the attributes processor.

There are three sources for the value of attributes the caller might want to insert. See here for additional details).

• static value
• value of a different attribute (e.g. from a different row in the attributes Record Batch)
• from context (e.g. from metadata, or auth information)
  • this will require some changes to OtapPdata as we'll need to keep context (metadata) from things like the gRPC request headers, BatchArrowRecord headers, information. We'll also need to modify the the gRPC receivers to populate this metadata.